https://bugs.kde.org/show_bug.cgi?id=511157
Bug ID: 511157
Summary: KWin/Wayland 6.5.0 freezes DP monitor on HDMI or
Thunderbolt hot-plug, 'Mode Validation Warning' in
logs
Classification: Plasma
Product: kwin
Version First 6.5.0
Reported In:
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: multi-screen
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 186188
--> https://bugs.kde.org/attachment.cgi?id=186188&action=edit
This is the full output of running journalctl
SUMMARY
KWin/Wayland 6.5.0: DisplayPort monitor freezes on HDMI or Thunderbolt
hot-plug, amdgpu "Mode Validation Warning" in logs
STEPS TO REPRODUCE
1. Start a Plasma (Wayland) session on a computer with an AMD Ryzen 5 7430u
(Renoir graphics).
2. Use a single monitor connected via DisplayPort (e.g., 3440x1440 @ 120Hz).
3. Once the desktop is active, hot-plug a second monitor into the HDMI port.
OBSERVED RESULT
Here is a complete bug report, pre-filled with all the information we've
gathered. You can copy and paste this directly into the KDE bug tracker.
SUMMARY
KWin/Wayland 6.5.0: DisplayPort monitor freezes on HDMI or Thunderbolt
hot-plug, amdgpu "Mode Validation Warning" in logs
STEPS TO REPRODUCE
Start a Plasma (Wayland) session on a computer with an AMD Ryzen 5 7430u
(Renoir graphics).
Use a single monitor connected via DisplayPort (e.g., 3440x1440 @ 120Hz).
Once the desktop is active, hot-plug a second monitor into the HDMI port or
with a Thunderbolt cable.
OBSERVED RESULT
The primary DisplayPort monitor freezes after a moment. The image is static and
does not update. The newly connected HDMI monitor does not receive a signal
(remains black).
The system itself does not crash (e.g., the mouse cursor can still move, but
its image is not updated on the frozen screen). Unplugging the HMDI or
thunderbolt cable returns everything to normal on the DisplayPort connection.
The kernel log (journalctl -k -b -1 | grep -iE
"(amdgpu|drm|kwin|error|failed)") shows the following error spammed at the
moment of the hot-plug: amdgpu 0000:05:00.0: [drm] Mode Validation Warning:
Total vertical active bandwidth failed validation.
EXPECTED RESULT
Both monitors should become active. The Plasma desktop should extend or mirror
to the newly connected HDMI or Thunderbolt monitor, and the primary DisplayPort
monitor should remain responsive.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux running 6.17.5.arch1-1
KDE Plasma Version: 6.5.0
KDE Frameworks Version: 6.19.0
Qt Version: 6.10.0
ADDITIONAL INFORMATION
1. This is a Wayland-Specific issue: This bug ONLY occurs in the Plasma
(Wayland) session. The exact same hot-plug procedure in a Plasma (X11) session
works perfectly every time.
2. As far as I can tell, this is not a new kernel issue: This bug was tested
and confirmed on two different kernels:
linux (mainline): 6.17.5-arch1-1
linux-lts (Long-Term Support)
The behavior is identical on both kernels.
3. Hardware:
Machine: Blackview MP100 mini pc
CPU/APU: AMD Ryzen 5 7430u with Radeon Graphics (Renoir)
4. KWin Support Information:
Version
=======
KWin version: 6.5.0
Qt Version: 6.10.0
Qt compile version: 6.10.0
XCB compile version: 1.17.0
Operation Mode: Wayland
Output backend
==============
Name: DRM
Atomic Mode Setting on GPU 0: true
Screens
=======
Number of Screens: 1
Screen 0:
---------
Name: DP-1
Enabled: 1
Geometry: 0,0,3440x1440
Physical size: 797x334mm
Scale: 1
Refresh Rate: 120000
Adaptive Sync: never
Compositing
===========
Compositing is active
Compositing Type: OpenGL
OpenGL vendor string: AMD
OpenGL renderer string: AMD Radeon Graphics (radeonsi, renoir, ACO, DRM 3.64,
6.17.5-arch1-1)
OpenGL version string: 4.6 (Core Profile) Mesa 25.2.5-arch1.2
OpenGL platform interface: EGL
OpenGL shading language version string: 4.60
Driver: Unknown
GPU class: Unknown
OpenGL version: 4.6
GLSL version: 4.60
Mesa version: 25.2.5
X server version: 1.24.1
Linux kernel version: 6.17.5
Direct rendering: Requires strict binding: no
Virtual Machine: no
OpenGL 2 Shaders are used
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